WASHINGTON — Protesters from Occupy DC, facing a clampdown on their encampment on Monday, stripped down for a topless street party outside a black-tie gala for Washington’s biggest movers and shakers. President Barack Obama and his wife Michelle topped the guest list for the 99th gathering of the exclusive Alfalfa Club, which convenes once a year in a five-star hotel for a lavish dinner and some witty speech-making.

Outside, up to 200 members of the local offshoot of Occupy Wall Street pogo-danced to Twisted Sister’s “We’re Not Gonna Take It” and Public Enemy’s “Fight the Power” as bemused police officers looked on behind barricades. Leading the revelers were several young women who gleefully bared their breasts, including one who wrote “freedom of expression” on the belly of another. Several men also stripped to the waist despite the winter chill. But there was a flash of tension as well when some Alfalfa Club invitees passed through the protesters, including one man who found himself in a staring match with a female protester before he was hit with a handful of glitter.

.. “I’d never heard of the Alfalfa Club before,” said protester David Varrows, 64, a Washington artist who turned up in tuxedo, a pig’s nose and a sign that read “Brother, can you spare a billion?”